Reciprocating compressor

ABSTRACT

A reciprocating compressor comprising a cylinder block ( 3 ) having formed therein a plurality of cylinders ( 11 ), a shaft rotatably passing through the cylinder block and pistons engaged in reciprocating movement inside the cylinders ( 11 ) as the shaft rotates, which is installed by fastening mounting leg parts ( 31 ) disposed at the cylinder block ( 3 ) at mounting positions, is characterized in that the mounting leg parts are each constituted with a connecting portion ( 31   a ) extending from the cylinder block  3  and a projected portion ( 31   b ) formed continuously to the connecting portion to project on one side or both sides of the connecting portion along the tightening direction and that the projected portion ( 31   b ) has a lower level of rigidity compared to the connecting portion ( 31   a ). The reciprocating compressor eliminates the need for rigorous management of the piston clearance by assuring firm installation via the mounting leg parts and also assuring smooth movement of the pistons with the extent of cylinder deformation kept within the allowable range.

TECHNICAL FIELD

The present invention relates to a reciprocating compressor which isinstalled by fastening mounting leg parts of the cylinder block atspecific positions with mounting bolts or the like.

BACKGROUND ART

A reciprocating compressor includes a cylinder block having a pluralityof cylinders formed therein, a shaft rotatably disposed so as to passthrough the cylinder block and pistons engaged in reciprocating movementinside the cylinders as the shaft rotates. It is installed at a specificlocation such as an engine compartment by fastening and locking mountingleg parts formed at the external circumferential surface of the cylinderblock or the like at specific positions with mounting bolts or the like.

While the mounting leg parts formed at the cylinder block or the likemay assume any of various structures, it is essential that they befirmly locked at the mounting positions. For this reason, in thestructure disclosed in Japanese Unexamined Utility Model Publication No.H2-43478, having mounting leg parts with cylindrical front ends formedat the external circumference of the compressor main unit as anintegrated part thereof and bolt insertion holes formed at thecylindrical front ends so as to extend along a direction orperpendicular to the axis of the compressor main unit, the mountingbolts passing through the bolt insertion holes are fastened to mountingbrackets locked onto mounting eyes.

Another compressor mounting structure that is widely known in therelated art (see Japanese Unexamined Patent Publication No. 2001-182650)is adopted in conjunction with a compressor having a bore housing havinga plurality of cylinders formed therein and a side housing having housedtherein a piston drive means. Two main mounting portions, each having amounting hole or a mounting groove at which a main locking bolt means ismounted, are disposed at the external circumferential surface of theside housing and at least one sub-mounting portion having a mountinghole or a mounting groove at which a sub locking bolt means is mountedis disposed at the external circumferential surface of the bore housingso as to allow the compressor to be locked at the main mounting portionswhile it is held at the sub-mounting portion. This structure allows thecompressor to be installed without having to mount the sub-mountingportion with an excessive level of firmness which may cause deformationof the bore housing.

However, the cylinder block of the compressor is often constituted of analuminum alloy in order to keep down the weight, and there is a problemin that as the mounting leg parts are fastened by tightening mountingbolts as in the structure described above, the tightening pressureoccurring while the mounting leg parts are fastened deforms the mountingleg parts and the deformation propagated to the cylinders compromisesthe shape of the cylinders, which, in turn, prevents smooth movement ofthe pistons. While the piston clearance may be set to a large value bytaking into consideration such cylinder deformation, the quantity ofworking fluid leaking along the side surfaces of the pistons is bound toincrease when the piston clearance is large, which will require morerigorous allowance management. If the management is not rigorous enough,the performance of the compressor will become poorer due to the leakage.

While the problem described above may be solved to some extent byadopting the structure disclosed in the second publication describedabove, the structure in which the level of the tightening force withwhich the sub-mounting portion at the cylinder block is fastened isrelatively low is not necessarily suited for an application in acompressor installed in a vehicle or the like subjected to a great dealof vibration.

Accordingly, an object of the present invention is to provide areciprocating compressor that does not require rigorous management ofthe piston clearance while assuring secure installation via the mountingleg parts and also assuring smooth movement of the pistons by keepingthe extent of cylinder deformation occurring during the installationwithin an allowable range.

DISCLOSURE OF THE INVENTION

In order to achieve the object described above, a reciprocatingcompressor according to the present invention comprising a cylinderblock having formed therein a plurality of cylinders, a shaft rotatablypassing through the cylinder block and pistons engaged in reciprocatingmovement inside the cylinders as the shaft rotates, which is installedby fastening mounting leg parts disposed at the cylinder block atmounting positions, is characterized in that the mounting leg parts areeach constituted with a connecting portion extending from the cylinderblock and a projected portion formed continuously to the connectingportion to project on one side or both sides of the connecting portionalong the tightening direction and that the projected portion has alower level of rigidity compared to the connecting portion.

Accordingly, as the mounting leg parts disposed at the cylinder blockare fastened onto the mounting positions with mounting bolts or the liketo install the compressor at the installation location, the tighteningpressure occurring as the mounting bolts are tightened causesdeformation of the mounting leg parts, but since the projected portionsformed at the mounting leg parts are formed to have a relatively lowlevel of rigidity compared to the connecting portions, the deformationoccurring during the tightening process manifests in a concentratedmanner at the projected portions. Thus, the deformation of the mountingleg parts occurring during the tightening process can be absorbed at theprojected portions, reducing the extent to which the tightening pressureis transmitted to the cylinders via the connecting portions, which makesit possible to ensure that the extent of the cylinder deformation iskept within the allowable range.

Alternatively, a reciprocating compressor according to the presentinvention comprising a cylinder block having formed therein a pluralityof cylinders, a shaft rotatably passing through the cylinder block andpistons engaged in reciprocating movement inside the cylinders as theshaft rotates, which is installed by fastening mounting leg partsdisposed at the cylinder block at mounting positions, is characterizedin that the mounting leg parts are each constituted with a connectingportion extending from the cylinder block and a projected portion formedcontinuously to the connecting portion to project on one side or bothsides of the connecting portion along the tightening direction and thatthe sectional area of the projected portions is set smaller than thesectional area of the connecting portions.

In this structure, while the mounting leg parts are caused to becomedeformed by the tightening pressure occurring as the mounting bolts aretightened when the mounting leg parts disposed at the cylinder block arefastened at the mounting positions with the mounting bolts to lock thecompressor at the installation location, the deformation occurringduring the tightening process manifests first and foremost at theprojected portions since the sectional area of the projected portionsformed at the mounting leg parts is set smaller than the sectional areaof the connecting portions. Thus, the deformation of the mounting legparts occurring during the tightening process can be absorbed at theprojected portions, reducing the extent to which the tightening pressureis transmitted to the cylinders via the connecting portions, which makesit possible to ensure that the extent of the cylinder deformation iskept within the allowable range.

In either of the structures described above, a bolt insertion hole atwhich a mounting bolt is inserted may be formed at the center of eachprojected portion and thinning out the wall thickness of the connectingportion along the direction running perpendicular to the bolt insertionhole is not required. In such a case, sufficient rigidity of theconnecting portions can be assured with an even higher level ofreliability.

By forming the projected portions so that they assume a cylindricalshape externally, uniform deformation may be induced at the projectedportions around the axes thereof during the tightening process (claim4). As a further alternative, a bolt insertion hole at which a mountingbolt is inserted may be formed at the center of each projected portionwith at least one projected portion disposed on one side or both sidesof the corresponding connecting portion along the tightening directionhaving a length along the axial direction set approximately equal to orgreater than the internal diameter of the bolt insertion hole, so as toor allow the deformation manifesting as the bolt is tightened toconcentrate at the projected portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation of an external view of a reciprocatingcompressor according to the present invention;

FIG. 2 is a sectional view of the reciprocating compressor according tothe present invention taken along line X-X in FIG. 3(b);

FIG. 3 shows the rear-side cylinder block in the compressor shown inFIG. 1, with FIG. 3(a) presenting a side elevation and FIG. 3(b) showingan end surface of the cylinder block, viewed from the side where therear-side cylinder head is located;

FIG. 4 presents an example of another structure that may be adopted inthe mounting leg parts;

FIG. 5 shows a cylinder block that does not include crush zones at themounting leg parts, with FIG. 5(a) presenting a side elevation and FIG.5(b) showing an end surface viewed from the cylinder head side; and

FIG. 6 is a graph provided to facilitate the comparison of the extent ofcylinder deformation occurring as the mounting leg portions are fastenedin the structure shown in FIG. 5 which does not include crush zones atthe mounting leg parts and the extent of deformation occurring as themounting leg portions are fastened in the structure according to thepresent invention, which does include crush zones.

BEST MODE FOR CARRYING OUT THE INVENTION

The following is an explanation of embodiments of the present invention,given in reference to the drawings. A reciprocating compressor 1 shownin FIGS. 1 through 3, which is used in a refrigerating cycle with acoolant used as a working fluid, comprises a front-side cylinder block2, a rear-side cylinder block 3 mounted at the front-side cylinder block2, a front-side cylinder head 5 mounted at the front side (the left sidein FIGS. 1 and 2) of the front-side cylinder block 2 via a valve plate 4and a rear-side cylinder head 7 mounted at the rear side (the right sidein FIGS. 1 and 2) of the rear-side cylinder block 3 via a valve plate 6.The front-side cylinder head 5, the front-side cylinder block 2, therear-side cylinder block 3, and the rear-side cylinder head 7 arefastened together along the axial direction with a tightening bolt (notshown) and constitute the housing for the whole compressor.

At the cylinder blocks 2 and 3 a shaft support hole 10 that rotatablysupports a shaft 9 to be detailed later, a plurality of (5) cylinders 11extending parallel to the shaft support hole 10 and disposed over equalintervals on a circumference of a circle centered on the shaft 9, twodischarge passages 12 extending parallel to the cylinders 11 and intakepassages 13 through which a low pressure working fluid flows, areformed. The discharge passages 12 communicate with each other via aguide passage 12 a, and individually communicating with a dischargechamber 14 formed at the front-side cylinder head 5 to be detailed laterand the other discharge passage communicating with a discharge chamber14 formed at the rear-side cylinder head 7. In addition, one of thedischarge passages 12 is connected to a discharge port 16 through whichthe working fluid is let out to an external cycle via a passing hole 15formed at the valve plate 6 or the like. The intake passages 13 areconnected to a swashplate housing chamber 21 to be detailed below andthey are further connected with a low-pressure passage 18 communicatingwith intake chambers 17 at the cylinder heads 5 and 7 via the swashplatehousing chamber 21. A double-ended piston 19 is slidably inserted ateach cylinder 11. It is to be noted that reference numeral 20 in FIG. 3indicates a bolt insertion hole formed between adjacent cylinders 11, atwhich a tightening bolt is inserted.

The swashplate housing chamber 21 formed by assembling the front-sidecylinder block 2 and the rear-side cylinder block 3 is present insidethe cylinder blocks, and the shaft 9 inserted at the shaft support hole10 formed at the front-side cylinder block 2 and the rear-side cylinderblock 3 with one end projecting out through the front-side cylinder head5 and fixed to the armature of an electromagnetic clutch (not shown) isdisposed in the swashplate housing chamber 21.

A swashplate 22, which rotates as one with the shaft 9 inside theswashplate housing chamber 21, is fixed to the shaft 9. The swashplate22 is rotatably supported at the front-side cylinder block 2 and therear-side cylinder block 3 via thrust bearings 23, with thecircumferential edge thereof held at shoe pockets 25 formed at thecenter of the double ended pistons 19 via semispherical shoes 24disposed along the front/rear direction. Thus, as the shaft 9 rotatescausing the swashplate 22 to rotate, the rotating movement is convertedto reciprocal linear motion of the double ended pistons 19 via the shoes24, and then as the double ended pistons 19 engage in the reciprocalmotion, the volumetric capacity of the compression space 26 formedinside each cylinder 11 between the piston 19 and the valve plates 4 and6 is varied.

An intake hole 27 and a discharge hole 28 are formed at each valve plate4 and 6, in correspondence to each of the cylinders 11. In addition, theintake chambers 17, in which the working fluid to be supplied to thecompression spaces 26 is stored, and the discharge chambers 14 in whichthe working fluid discharged from the compression spaces 26 is stored,are defined. The intake chambers 17 are allowed to communicate with thecompression spaces 26 via the intake holes 27 formed at the valve plates4 and 6, whereas the discharge chambers 14 formed continuously aroundthe intake chambers 17 are allowed to communicate with the compressionspaces 26 via the discharge holes 28 formed at the valve plates 4 and 6.

The intake holes 27 are opened/closed with intake valves 29 disposed atthe end surfaces of the valve plates 4 and 6 toward the cylinder blocks,whereas the discharge holes 28 are opened/closed with discharge valves30 disposed at the end surfaces of the valve plates 4 and 6 toward thecylinder heads.

Thus, during an intake stroke in which the volumetric capacity of thecompression space 26 increases as the piston 19 moves reciprocally, theworking fluid is taken into the compression spaces 26 from the intakechamber 17 via the intake hole 27 and the intake valve 29, whereasduring a compression stroke in which the volumetric capacity of thecompression space 26 decreases, the working fluid having been compressedin the compression space 26 is discharged via the discharge hole 28 andthe discharge valve 30 to the discharge chamber 14 and is forced to theoutside of the compressor from the discharge port 16 via the dischargepassage 12.

At the external circumferential surfaces of the cylinder blocks 2 and 3described above, mounting leg parts 31 used when installing thecompressor at a specific mounting location in an engine room or the likeare formed at positions symmetrical to each other relative to the axis(upper and lower positions in the figure).

The mounting leg parts 31 each include a connecting portion 31 aextending from the cylinder block 2 or 3 along a substantially radialdirection and a projected portion 31 b formed continuous to theconnecting portion 31 a so as to project on one side of the connectingportion along the tightening direction running perpendicular to theshaft 9. At the center of the projected portion 31 b, a bolt insertionhole 32 at which a mounting bolt (not shown) to interlock with amounting hole formed at the mounting area is inserted, is formed torange over to the connecting portion 31 a. In addition, the wallthickness of the connecting portion 31 a at the mounting leg part 31 isnot thinned out from the direction running perpendicular to the boltinsertion hole 32.

The mounting leg parts 31 are formed as an integrated part of thecylinder blocks 2 and 3 by using an aluminum alloy, with the projectedportions 31 b formed to have a lower level of rigidity compared to theconnecting portions 31 a to form more deformable crush zones. Morespecifically, the rigidity at each projected portion 31 b is set lowerthan the rigidity at the corresponding connecting portion by setting thearea of a section of the projected portion 31 b perpendicular to theaxial line of the bolt insertion hole 32 smaller than the area of asection of the connecting portion 31 a. In this example, the sectionalarea of the projected portion is reduced by forming the bolt insertionhole 32 to have a uniform internal diameter over the full range andsetting the external diameter of the projected portion 31 b to arelatively small value so as to form a stage at the surface over whichthe connecting portion 31 a turns into the projected portion 31 b.

In addition, the projected portion 31 b in the structure described aboveis formed in a cylindrical shape with a uniform thickness, with thelength of the projected portion 31 b along the axial direction setapproximately equal to or greater than the internal diameter of the boltinsertion hole 32.

In the structure described above, as a mounting bolt is inserted at thebolt insertion hole 32 from the side on which the projected portion 31 bis formed (from the direction indicated with the arrow in FIG. 3(b)) andthe corresponding mounting leg part 31 is fastened by interlocking themounting bolt at a screw hole formed at a specific mounting position,the mounting leg part 31 becomes deformed due to the tighteningpressure. However, since the level of rigidity of the projected portion31 b formed at the mounting leg part 31 is set lower than the rigidityof the connecting portion 31 a and the wall of the connecting portion 31a is not thinned out, the deformation occurring during the tighteningprocess manifests at the projected portion 31 b in a concentratedmanner. Thus, the deformation of the mounting leg part 31 occurringduring the tightening process can be absorbed at the projected portion31 b, which disallows ready transmission of the tightening pressure tothe cylinder 11 via the connecting portion 31 a. Consequently, theextent of deformation of the cylinder 11 is kept within the allowablerange and the circularity of the cylinder can be maintained at a highdegree of accuracy, assuring smooth movement of the piston 19. Inaddition, since the extent of deformation of the cylinder 11 is reduced,a large piston clearance for assuring a comfortable margin for thedeformation of the cylinder 11 is not necessary. Moreover, rigorousallowance management for purposes of managing the working fluid leakingpast the side surface of the piston 19 is not required.

Furthermore, since the projected portion 31 b of the mounting leg part31 is formed in a cylindrical shape, the projected portion 31 b becomesdeformed with uniformity around the axis during the tightening process.Thus, with the projected portion 31 b allowed to become deformed evenly,the extent to which the cylinder 11 becomes deformed can be reduced. Inaddition, since the length of the projected portion 31 b along the axialdirection is set approximately equal to or greater than the diameter ofthe bolt insertion hole 32, the deformation occurring as the mountingbolt is tightened can be concentrated at the projected portion 31 b withan even higher degree of reliability, which also makes it possible toreduce the extent of deformation of the cylinder 11.

While the projected portion 31 b is formed only on one side of theconnecting portion along the tightening direction in the exampledescribed above, the projected portion 31 b may be disposed on each sidealong the tightening direction, as shown in FIG. 4(a). Namely, themounting leg portion 31 may include projected portions 31 b projectingon the two sides along the tightening direction at the connectingportion 31 a extending from the cylinder block 2 or 3 substantiallyalong the radial direction with the bolt insertion hole 32 formed tohave a uniform diameter ranging from one of the projected portions 31 bthrough the other projected portion 31 b and the sectional area of theprojected portions set smaller by setting the external diameter of theprojected portions 31 b smaller than the diameter of the connectingportion 31 a so as to form a crush zone with lower rigidity at each endof the bolt insertion hole 32.

In addition to advantages similar to the previous structural example,this structure, which allows the deformation occurring during thetightening process to be dispersed onto the two sides of the connectingportion 31 a, makes it possible to reduce the extent to which thetightening force is communicated to the cylinder 11 via the connectingportion 31 a with an even higher degree of reliability.

While the rigidity at the projected portions 31 b is set smallerrelative to the rigidity at the connecting portions by setting theexternal diameter of the projected portions 31 b to a smaller value inthe structures described above, the rigidity of the projected portionsmay be set smaller by adopting structures other than those explainedabove.

For instance, in a structure having a projected portion 31 c formed oneach side a long the tightening direction at each mounting leg part 31,the projected portions 31 c may be formed so that their exteriors rangeuniformly to the external contour of the connecting portions 31 awithout creating stages between the projected portions and theconnecting portion 31 a, and the internal diameter of the bolt insertionhole 32 may be set larger than the areas where the projected portions 31c are present relative to the internal diameter in the area over whichthe connecting portion 31 a is present. In this case, with the sectionalarea of the projected portions 31 c set smaller than the sectional areaof the connecting portion 31 a, a crush zone with lower rigidity isformed at each end of the bolt insertion hole 32. It is to be noted thatsince other structural features such as the projected portions 31 c eachformed in a cylindrical shape with a uniform thickness and the length ofthe projected portions 31 b along the axial direction set substantiallyequal to or greater than the internal diameter of the bolt insertionhole 32 are identical to those of the previous structural examples,their explanation is omitted.

This structure, too, makes it possible to concentrate the deformationoccurring during the tightening process at the projected portions 31 c,which, in turn, reduces the extent to which the mounting bolt tighteningforce is transmitted to the cylinder 11 via the connecting portion 31 a,thereby achieving advantages similar to those of the previous structuralexamples.

Alternatively, crush zones with lower rigidity than the connectingportion may be formed by using a different material to constitute theprojected portions, as shown in FIG. 4(c). Namely, in a structure havinga projected portion on each side along the tightening direction at theconnecting portion 31 a of the mounting leg part 31, which extends fromthe cylinder block 2 or 3 substantially along the radial direction, theconnecting portion 31 a may be constituted of an aluminum alloy, as arethe cylinder blocks 2 and 3, the projected portions 31 d may be formedby using a synthetic resin with a lower level of rigidity compared tothe aluminum alloy, and the connecting portion and the projectedportions may be coupled by an appropriate means such as press fitting orbonding so as to form low-rigidity crush zones at the two ends of thebolt insertion hole 32. It is to be noted that since other structuralfeatures such as the projected portions 31 d each formed in acylindrical shape with a uniform thickness and the length of theprojected portions 31 d along the axial direction set substantiallyequal to or greater than the internal diameter of the bolt insertionhole 32 are identical to those of the previous structural examples,their explanation is omitted.

This structure, too, makes it possible to concentrate the deformationoccurring during the tightening process at the projected portions 31 dconstituted of a synthetic resin, which, in turn, reduces the extent towhich the mounting bolt tightening force is transmitted to the cylinder11 via the connecting portion 31 a, thereby achieving advantages similarto those of the previous structural examples. In addition, in thisstructure, the projected portions 31 d may be formed with theirexteriors ranging uniformly and continuously to the external contour ofthe connecting portion 31 a without creating stages between theprojected portions 31 d and the connecting portion 31 a with the boltinsertion hole 32 formed to have a uniform internal diameter rangingfrom one of the projected portions 31 d through the other projectedportion 31 d, and since the connecting portion 31 a and the projectedportions 31 d can be machined separately, the mounting leg part 31 canbe formed with greater ease.

A comparison of the extent of deformation occurring at cylinders 11 whenthe mounting leg parts 31 are fastened with mounting bolts by using thecylinder blocks 2 and 3 having the projected portions 31 b, 31 c or 31 dforming crush zones at the mounting leg parts 31 as described above andby using a cylinder block 36 shown in FIG. 5 with no projected portionsto form crush zones included at the mounting leg parts 31 and the wallthickness reduced over an area 35 from the direction runningperpendicular to the bolt insertion holes 32 provided the resultspresented in FIG. 6. The bore numbers in FIG. 6 were assigned toidentify the individual cylinders, with “No. V” assigned to the cylinder11 located closest to the bottom where the mounting leg parts 31 arepresent in FIGS. 3 and 5, and “No. IV”, “No. III”, “No. II” and “No. I”sequentially assigned to the remaining cylinders 11 by moving clockwisefrom the cylinder No. V. The extents of deformation occurring as themounting bolts inserted at the bolt insertion holes 32 from the leftside in FIGS. 3 and 5 were tightened were compared.

As the results of the comparison clearly indicate, the extent ofdeformation of the cylinders 11 that occurred as the mounting bolts weretightened in either of the structures, was lessened when crush zoneswere formed at the mounting leg parts 31, compared to the extent ofdeformation at the cylinders 11 in the structure that did not includeany crush zones. The greatest difference in the extent of deformationmanifested at the cylinders (V) closest to the mounting leg parts 31.

It is to be noted that while the rigidity of the projected portions islessened relative to the rigidity of the connecting portions by settingthe sectional area of the projected portions smaller than the sectionalarea of the connecting portions or by forming the projected portionswith a material different from the material used to form the connectingportions in the structural examples described above, the features of thestructural examples described above may be adopted in combination asappropriate. In addition, as an alternative to or as an additionalfeature to the structural examples described above, different levels ofrigidity may be achieved chemically through a heat treatment or thelike.

INDUSTRIAL APPLICABILITY

As described above, the reciprocating compressor according to thepresent invention comprising a cylinder block having a plurality ofcylinders formed therein, a shaft rotatably passing through the cylinderblock and pistons engaged in reciprocal motion in the cylinders as theshaft rotates, which is installed by fastening mounting leg partsdisposed at the cylinder block at mounting positions, is characterizedin that the mounting leg parts each include a connecting portionextending from the cylinder block and a projected portion formedcontinuous to the connecting portion and projecting on one side or bothsides of the connecting portion along the tightening direction. Sincethe projected portions are formed so as to have a lower level ofrigidity compared to the connecting portions, the deformation occurringas the mounting bolts are tightened can be concentrated at the projectedportions, which makes it possible to assure smooth movement of thepistons by keeping down the extent of cylinder deformation within theallowable range while assuring firm installation of the compressor viathe mounting leg parts. As a result, rigorous management of the pistonclearance is no longer required and a greater tolerance can be assumedfor the piston clearance.

1. A reciprocating compressor comprising: a cylinder block having formedtherein a plurality of cylinders, a shaft rotatably passing through saidcylinder block and pistons engaged in reciprocating movement inside saidcylinders as said shaft rotates, which is installed by fasteningmounting leg parts disposed at said cylinder block at mountingpositions, wherein said mounting leg parts are each constituted with aconnecting portion extending from said cylinder block and a projectedportion formed continuously to said connecting portion to project on oneside or both sides of said connecting portion along the tighteningdirection; and wherein said projected portion has a lower level ofrigidity compared to said connecting portion so as to concentratedeformation occurring during installation into said projected portion.2. A reciprocating compressor comprising: a cylinder block having formedtherein a plurality of cylinders, a shaft rotatably passing through saidcylinder block and pistons engaged in reciprocating movement inside saidcylinders as said shaft rotates, which is installed by fasteningmounting leg parts disposed at said cylinder block at mountingpositions, wherein said mounting leg parts are each constituted with aconnecting portion extending from said cylinder block and a projectedportion formed continuously to said connecting portion to project on oneside or both sides of said connecting portion along the tighteningdirection; and wherein the sectional area of said projected portion isset smaller than the sectional area of said connecting portion so as toconcentrate deformation occurring during installation into saidprojected portion.
 3. A reciprocating compressor according to claim 1,wherein a bolt insertion hole at which a mounting bolt is inserted isformed at the center of each projected portion and the wall thickness ofsaid connecting portion is not thinned out along a direction runningperpendicular to said bolt insertion hole.
 4. (canceled)
 5. (canceled)6. A reciprocating compressor according to claim 2, wherein a boltinsertion hole at which a mounting bolt is inserted is formed at thecenter of each projected portion and the wall thickness of saidconnecting portion is not thinned out along a direction runningperpendicular to said bolt insertion hole.
 7. A reciprocating compressoraccording to claim 1, wherein the external shape of said projectedportion is cylindrical.
 8. A reciprocating compressor according to claim2, wherein the external shape of said projected portion is cylindrical.9. A reciprocating compressor according to claim 3, wherein the externalshape of said projected portion is cylindrical.
 10. A reciprocatingcompressor according to claim 1, wherein a bolt insertion hole at whicha mounting bolt is inserted is formed at the center of each projectedportion, with at least one projected portion disposed on one side orboth sides of said connecting portion having a length along the axialdirection set approximately equal to or greater than the internaldiameter of said bolt insertion hole.
 11. A reciprocating compressoraccording to claim 2, wherein a bolt insertion hole at which a mountingbolt is inserted is formed at the center of each projected portion, withat least one projected portion disposed on one side or both sides ofsaid connecting portion having a length along the axial direction setapproximately equal to or greater than the internal diameter of saidbolt insertion hole.
 12. A reciprocating compressor according to claim3, wherein a bolt insertion hole at which a mounting bolt is inserted isformed at the center of each projected portion, with at least oneprojected portion disposed on one side or both sides of said connectingportion having a length along the axial direction set approximatelyequal to or greater than the internal diameter of said bolt insertionhole.
 13. A reciprocating compressor according to claim 4, wherein abolt insertion hole at which a mounting bolt is inserted is formed atthe center of each projected portion, with at least one projectedportion disposed on one side or both sides of said connecting portionhaving a length along the axial direction set approximately equal to orgreater than the internal diameter of said bolt insertion hole.